Atomized particle lubrication of cup-shaped can bodies

ABSTRACT

Cup lubricating process and apparatus in which cup-shaped can bodies are controllably conveyed in spaced relationship to each other through a lubrication application chamber. Lubricant is atomized to particle sizes permitting them to be gas borne and introduced into such chamber from a plurality of locations about the travel path for can bodies. Apertures in the bottom wall of such chamber direct lubricant particles directly into the open ends of such can bodies for flow impingement deposition on internal surfaces thereof. Provision is made for augmenting surface deposition by electrically charging at least a portion of the gas-borne lubricant particles in such chamber and electrically grounding can bodies individually during passage through such chamber. Endless loop conveyor means are provided with adjustable features enabling a travel path to be adapted to differing dimension can bodies.

This is a division of application Ser. No. 068,065 filed June 30, 1987,which was a continuation-in-part of application Ser. No. 011,112 filedFeb. 5, 1987 (now U.S. Pat. No. 4,724,155 dated Feb. 9, 1988), which wasa continuation-in-part of application Ser. No. 681,630 filed Dec. 14,1984 (now abandoned), the entire disclosures of which are incorporatedherein by reference.

The present invention is concerned with controlling continuous in-linemovement and atomized particle lubrication of cup-shaped sheet metal canbodies during transfer between work stations in a can body fabricatingline.

An important contribution of the invention enables such lubrication tobe carried out in-line without substantial interruption of sequentialcan body fabricating steps. A can body travel path is establishedthrough a lubricant application chamber providing controlled passage ofcan bodies in spaced relationship to each other while minimizing contactof conveyance means with the can bodies in order to minimize blockinglubricant particle deposition. A desired lubricant coating, e.g. of thetype which eliminates the need for washing of the can bodies subsequentto fabrication, and before use, is obtained.

Other advantages and contributions of the invention are set forth inmore detail in describing apparatus as shown in the accompanyingdrawings, in which:

FIG. 1 is a schematic diagram of portions of a can body fabricating lineincluding in-line lubricating apparatus in accordance with theinvention,

FIG. 2 is a schematic perspective view, with portions cut away andomitted for clarity, of a portion of the cup lubricant depositionapparatus of the invention,

FIG. 3 is a schematic cross-sectional view, along a plane which isperpendicularly transverse to the direction of movement of can bodies,of lubricating apparatus in accordance with the invention,

FIG. 4 is a perspective view, with portions cut away and omitted forclarity, of lubrication apparatus in accordance with the invention,

FIG. 5 is a plan view showing adjustable means for supporting andstabilizing means during passage through lubricant deposition chamber inaccordance with the invention, and

FIG. 6 is a side elevational view of cup lubricating apparatus inaccordance with the invention.

During can-making operations, continuous-strip flat rolled sheet metal,such as flat rolled steel having a protective "organic coating" (theorganic polymer coatings used in the canning industry) is lubricated onboth its planar surfaces before being cut into blanks. Shallow cups areformed initially from blanks; usually at the blanking station.Subsequent forming operations, e.g. redrawing at other stations, arerequired to produce the extended side wall heights used in themanufacture of two-piece cans for soups and vegetables. Additionallubrication of the work product can be helpful in such subsequentforming operations where insufficient lubrication remains from the flatmetal lubrication stage due, e.g., to delays occurring before or betweenthe subsequent forming operations.

Liquid "wash" or dipping was previously available for lubricating cupsbut no successful method or means for atomized particle lubrication ofcup-shaped can bodies was known or commercially available. It was notrecognized that the electrostatic atomized lubricant particle depositionmethods relied on for lubrication of sheet metal in flat form could notbe readily or satisfactorily transferred to can body lubrication becausethe cup shaped sheet metal shielded the interior thereof fromelectrostatic forces.

The present invention enables atomized particle lubrication of bothinternal and external surfaces of cup-shaped can bodies to be carriedout, where and when needed for sequential forming operations, by methodsand means for controllably directing particles into a chamber locatedabove an atomizing chamber so as to achieve desired deposition on canbodies moving through such chamber.

In the schematic diagram of FIG. 1, sheet metal can stock having anorganic polymeric coating on both its planar surfaces, is fed from coil7 into sheet lubricator 8 in which both such surfaces are lubricated.Such lubricated can stock is fed directly into blanking and cuppingapparatus 9. Individual shallow cups, from apparatus 9, are thendirected along a travel path, which can include cup lubricationapparatus 15, and a subsequent forming operation at work station 18. Forexample, at work station 18 the can body is redrawn to a smallerdiameter and increased side wall height.

When supplemental lubrication is required, the cup-shaped sheet metalcan bodies are controllably conveyed, i.e. uniformly oriented in spacedrelationship to each other, during passage through a cup lubricationapparatus 15 which is placed in an operating mode for such purpose.

Referring to FIG. 2, lubrication apparatus 15 includes a lubricantdeposition chamber 20, through which horizontally-oriented travelpath(s) for can bodies extend as indicated by FIGS. 3, 4 and 6.

The lubricant deposition chamber 20 is defined by enclosure meansproviding a bottom wall 21, lateral side walls 22, 23, an exit wall 24,and entrance and top walls; an exit port for can bodies is providedthrough wall 24; the entrance and top walls are also omitted in theperspective view of FIG. 2. As taught herein, such chamber defining wallmeans are formed from rigid electrically non-conductive, plastic sheetstock, such as polypropylene, and do not require electrical grounding.

The desired lubricant is atomized to sizes permitting the lubricantparticles to be borne and transported by a gaseous medium. In oneembodiment, lubricant in liquid form, as supplied or established usingheat, is provided in lubricant reservoirs 25, 26. This lubricant sumparrangement is established by sump walls such as walls 27, 28 and acentral divider wall 30; such sump walls which define the reservoirs forlubricant can also be formed from plastic sheet stock. Individualatomizing means, such as 32, 33, are associated with each lubricantreservoir. Liquid lubricant is drawn from each reservoir and atomizedutilizing suitable commercially available atomizing means. Suitableheating means for controlling the temperature of the lubricant, such asheating element 34, are provided to controllably establish and/ormaintain desired lubricant temperature. Pressure in the atomizing sumpis augmented and/or controlled to provide desired particle flow byauxiliary pneumatic supply means 36, 37 which are connected to means forautomatically controlling pressure to selected levels.

Plural lubricant reservoirs, each with associated atomizing means andmeans for directing flow of gas-borne lubricant particles as in theillustrated embodiment, enable through teachings included hereinatomized lubricant particle deposition on internal and external surfacesof cup-shaped work product without interrupting line movement of suchwork product.

Travel paths for can bodies, such as 38 and 39 of FIG. 3, areestablished in a unique manner which contributes significant advantagesin supporting and stabilizing cups in desired orientation utilizingendless-belt loop means as shown and described in more detail inrelation to FIGS. 3-6.

The movement of such cup-shaped work product and of gas-borne lubricantparticles is controlled so as to direct such particles axially into openends of such can bodies during passage along an established travel path.For example, gas-borne particles are directed through apertures as shownin bottom wall 21 (FIGS. 2,3); such apertures are vertically below eachtravel path for can bodies so as to direct lubricant particles into theopen ends of such can bodies for flow impingement deposition on internalsurfaces thereof. Such bottom wall introduction of particles into thedeposition chamber can also provide at least a portion of the atomizedlubricant particles for deposition on external surfaces throughaugmented lateral flow impingement and/or electrostatic forces, astaught herein.

Deposition on such external surfaces by flow impingement can beimplemented by pneumatically introducing atomized particles throughapertures selectively located on laterally opposite sides of theelongated, horizontal travel path(s) for the can bodies.

Electrical charging wires can be distributed along the direction oftravel of can bodies throughout the lubricant deposition chamber 20 forelectrostatic charging of atomized lubricant particles. Such wiresextend across substantially the full lateral dimension of such chamber;and, can be selectively actuated preferably in at least the latter halfof the travel path through the deposition chamber.

The location and the number of apertures to be used, as well as thelocation of electrostatic charging wires can be selected. Since acup-shaped metal can body tends to shield its internal volume andsurfaces from electrostatic forces, direct flow impingement of internalsurfaces with atomized particles is preferably carried out initiallyafter entry of a can body into the deposition chamber in an attempt toavoid interference with such internal surface deposition. Lateral sideinjection of atomized particles can be carried out independently orcoordinated with electrostatic augmentation to the extent found usefulto accomplish desired deposition as such can bodies move along suchtravel path(s).

In accordance with the invention, endless-belt, electrically-insulatingloop means establish travel paths through the lubricant depositionchamber. They support and stabilize the sheet metal cups in spacedrelationship, and oriented axially as desired for purposes describedherein. As shown in FIG. 3, the endless-belt loops have a curvilinearexterior cross-sectional periphery which results in a tangential pointcontact with work product so as to minimize blockage of, or interferencewith, deposition of lubricant particles. The can bodies being fed to cuplubrication apparatus 15 are controllably conveyed in uniformly spacedrelationship through chamber 20; such can bodies are also uniformlyoriented; preferably with central axes substantially vertical as in theillustrated embodiment and with open ends directed downwardly.

Flexible, electrically non-conductive, plastic tubular material, such aspolyurethane round belting, available from Eagle Belting Co., DesPlaines, Ill., is used for endless-belt loops. The endless beltsstabilize and support cup-shaped work product during conveyance throughchamber 20. For example, in FIG. 3, loops 46, 47 contact the open endportions of the downwardly-oriented can body 48 to support its weight;and endless loops 50, 51 contact the side wall of can body 48 atdiametrically opposite sides to stabilize it in its upright position.

FIG. 4 depicts means for electrically grounding can bodies individuallyduring passage in spaced relationship through lubricant applicationchamber 20 when electrostatic energy is to be used to augmentflow-impingement particle deposition on the cup-shaped work product.Individual ground contact means are provided along at least a portion ofthe work product travel path for repetitious grounding of individual canbodies. Referring to the travel path defined by endless-belt loops 46,47 and 50, 51 for can bodies 54, 55 and 56, the latter are shown incontact with flexible metallic conductors 59, 61 during a portion of thepassage through chamber 20. Such flexible contact conductors aregrounded through wire 62, which is grounded to the support frame, orotherwise; other ground wires shown are similarly grounded. Exteriorsurfaces of such elongated grounding wires are electrically insulated asthey extend through the chamber 20 so as to avoid accumulation oflubricant particles and minimize current loss. For example, ground wire63 is covered by electrical insulation 66 for such purposes. However,the work product contact conductors are exposed to facilitate electricalgrounding of individual can bodies.

Flexible contacts are positioned so as to provide electrical contactwith one or more external surfaces of a can body, such as its closed endas shown, or at its side wall or at its flange. The type of groundingconductor is selected and/or positioned to minimize accumulation oflubricant particles. With electrical grounding of can bodies,electrically-charged gas-borne lubricant particles have an opportunity,not otherwise available, to be attracted to uncoated surface portions ofsuch can bodies.

The quantity of gas-borne particles introduced into chamber 20 isregulated by gas supplied to the lubricant sump atomizing chamber means.In a specific embodiment, gas flow from the atomizing chambers to thedeposition chamber is selectively adjusted to coating weight desired andto the speed of the line. At line speeds above a selected median andwhen greater coating weight is desired, the gas flow is increased; atline speeds below a selected median and lower coating weight, the gasflow is decreased. The "flow rate" of lubricant particles into theapplication chamber can thus be regulated by regulating gas flow, e.g.air, supplied to the lubricant-atomizing sump(s). Such gas can besupplied as a part of pneumatic atomizing and/or supplied or augmentedby regulating gas supplied separately to the sump(s) as shown in FIG. 3.Selection of the number and location of the apertures into the chamberis utilized, as described earlier, in achieving deposition on interiorand exterior surfaces.

For grounding purposes, an insulated wire, which is grounded, ispositioned along each work product travel path with non-insulatedgrounding contact means extending in the direction of work product.Flexible metallic conductors, exposed for electrical contact with theexterior of each can body, are electrically connected to the groundwires. A plurality of such flexible conductors are connected to eachground wire along each travel path so that plural periodic grounding ofthe exterior surface of each can body occurs during at least a portionof its controlled passage between entrance port 70 and exit port 72 ofthe lubricant deposition chamber 20; preferably in the latter half ofthat passage. Charging wires, such as 73, 74, 75, 76 and 77, arepositioned to extend laterally of the chamber; preferably charging wiresin the latter half of the passage, such as 75, 76, 77 are utilized whenelectrostatic augmentation is desired.

Referring to FIGS. 5 and 6, endless-belt loops for defining each travelpath for continuous-line passage through deposition chamber means areshown in plan and lateral side elevational views, respectively, alongwith pulley support means; for example, pulley means 78, 79 in the planeof the travel paths and guide pulley means 80, 81 (FIG. 6) in the returnpaths. Belt cleaning means 84 are located in the return paths for wipingor otherwise removing accumulated lubricant and grit from the endlesstubular belts before return to the can body travel paths.

Independent pulley wheels can be selected to establish dimensionallydiffering travel paths and/or the pulleys can be adjustably mountedalong their respective support shafts 88, 89 (FIG. 5). The number oftravel paths can be varied; also, the width between support loops andthe height of and width between stabilizing loops can be selected.

The tubular belts are preferably of curvilinear cross-sectionalconfiguration, e.g. circular, to minimize peripheral contact with canbodies being conveyed.

Use of pressurized flow and flow impingement forces for atomizedlubricant particle deposition on surfaces of a cup-shaped work productresults in continuous escape of particles from the deposition chamber20. Such particles escape from the chamber at can body entry and exitports 70, 72 (FIGS. 4,6). An important aspect of the invention is toefficiently and effectively gather such escaping flow-through lubricantparticles so as to avoid ambient atmospheric contamination, but also todo so in a manner to avoid interference with flow paths of the particleswithin chamber 20. For such purposes, hoods 90, 92 (FIG. 6) are placedvertically above inlet and exit ports 70, 72, respectively. Also, thesehoods are placed to extend across the full width of such ports; and,further are exhausted centrally, or at a plurality of spaced locationsalong the hood rather than being exhausted at one end of a hood. Anexhaust conduit 94 is connected to a driven exhaust means indicatedschematically at 96. Exhaust apparatus manufactured to meet suchrequirements is available commercially from Smog Eaters, Inc. ofGooding, Id.

Data for a specific embodiment for carrying out the invention are setforth below:

    ______________________________________                                        Chamber 20                                                                    Longitudinal length (direction                                                                    37"                                                       of can travel)                                                                Lateral width (transverse to                                                                      44"                                                       direction of movement of                                                      can bodies)                                                                   Height              24"                                                       Wall material (thickness)                                                                          1/2"                                                     (commercial polypropylene sheet)                                              Lubricant                                                                     Commercially available Petrolatum                                             Heat to about 160 F.                                                          Atomizer                                                                      Model #1/8-JJ-SS-J22D-SS                                                      Spraying System Inc.                                                          Wheaton, Ill. 60187                                                           Endless-Belt Loops  1/2" diameterpoly-                                                            urethane tubing                                           Charging wire,      about 15,000 to 32,000                                    DC potential        volts (avoiding leakage                                                       of current, arcing or                                                         corono discharge)                                         Line Speed (adaptable to commercial can-making line                           practice)                                                                     For Can sizes 211 × 400,                                                                    typically                                                 300 × 407 and 303 × 406                                                               150 fpm                                                   Lubricant Particle Size and Gas Pressure Transport                            Particle size -                                                               about 25 microns at 20 psi                                                    about 20 microns at 30 psi                                                    ______________________________________                                    

Air pressure supplied to sumps--about 30 psia

Can sizes are expressed in diameter and height; the 211×400 (2-11/16"diameter, 4" height) is a typical soup can, 300×407 is a typical petfood can, and the 303×406 is typically used for fruits and vegetables.

While specific data, including materials, dimensions and configurations,have been set forth or shown for purposes of describing the invention,variations of those specifics would be available to those skilled in theart in the light of the present teachings. Therefore, reference to theappended claims is an added requirement for purposes of defining thescope of the patentable subject matter.

I claim:
 1. Apparatus for providing atomized liquid lubrication of interior and exterior surfaces of cup-shaped sheet metal can bodies while continuously moving such can bodies along a longitudinally-extended travel path through a can body fabricating line comprising, in combinationa lubricant source means providing lubricant in liquid form, a lubricant deposition chamber, means defining a horizontally-oriented travel path for can bodies through such deposition chamber, atomizing chamber means including atomizing means for converting such liquid lubricant into particles capable of being pneumatically transported by gas under pressure supplied to such atomizing chamber, such lubricant deposition chamber being defined by enclosure means including lateral side wall means on opposite lateral sides of such longitudinally-extended horizontally-oriented travel path, floor means below such travel path, top wall means above such travel path, and longitudinal end walls defining respective entrance and exit openings for can bodies entering into and exiting from such deposition chamber, such atomizing chamber means being located vertically below such deposition chamber and separated therefrom by such floor means; means for supplying cup-shaped can bodies having a closed end wall and a side wall extending longitudinally therefrom symmetrically with a can body central longitudinal axis to define an open end longitudinally opposite such can body closed end wall, such can bodies including flange metal extending radially outwardly from such open end in a plane substantially perpendicularly transverse to such central longitudinal axis, conveyance means for controlling continuous-line passage of such can bodies in spaced relationship to each other through such lubricant deposition chamber, such conveyance means defining such horizontally-oriented travel path through such deposition chamber along which such can bodies are oriented open end down with their central longitudinal axes substantially vertical in parallel relationship, and means for pneumatically directing movement of gas-borne atomized lubricant particles into the lubricant deposition chamber including apertures defined in the floor means of such deposition chamber below such horizontal travel path for directing atomized lubricant particles directly into open ends of such can bodies from apertures vertically below such open ends and extending along such travel path for deposition by flow impingement on internal surfaces of such can bodies during such continuous-line passage.
 2. The apparatus of claim 1 in whichsuch lubricant source means includes a plurality of lubricant reservoir means located in such atomizing chamber means, such atomizing chamber means is located vertically below such deposition chamber, and is subdivided vertically into a pair of atomizing chambers, each with an associated atomizing means for supplying such lubricant particles within its atomizing chamber and, in which such means for pneumatically directing gas-borne particles into such deposition chamber includes pressurized gas supply means for each such atomizing chamber, and each such atomizing chamber communicates with such deposition chamber.
 3. The apparatus of claim 2 in whichsuch means for directing gas-borne particles into such lubricant deposition chamber further includes apertures in lateral side wall means for directing lubricant particles into such deposition chamber.
 4. The apparatus of claim 1 includingadditional apertures at a level above such bottom wall means for introducing gas-borne lubricant particles into such deposition chamber from each lateral side of such travel path for deposition of at least a portion of such particles on external surfaces of such can bodies due to flow impingement with such external surfaces.
 5. The structure of claim 1 in whichsuch means for pneumatically directing movement of such gas-borne lubricant particles further includes gas flow passage means between such lubricant atomizing means and such lubricant deposition chamber leading to additional apertures defined in lateral side walls of such lubricant deposition chamber for introducing gas-borne lubricant particles from a plurality of locations positioned laterally of such travel path for can bodies and at a level above such bottom wall means, such deposition chamber enclosure means being non-electrically conductive, and further including electrical charging means located in space relationship from the closed end of such can bodies for electrically charging at least a portion of such pneumatically-directed gas-borne lubricant particles in such chamber for deposition on such can bodies, and means for electrically grounding external surfaces of such can bodies by individually contacting the external surface of each such can body a plurality of times during such passage along such travel path.
 6. The apparatus of claim 1 in whichfurther including in relation to such longitudinal end wall means defined entry and exit openings for can bodies at longitudinally opposite ends of such travel path, exhaust collection means located contiguous to each such opening for gathering gas-borne flow-through lubricant particles escaping from such openings.
 7. The apparatus of claim 6 in whichsuch enclosure means is formed from rigid, plastic non-electrically conductive sheet material, further including electrical means for electrostatically charging lubricant particles in such deposition chamber, and in which such can bodies are electrically grounded by a plurality of flexible electrical conductors positioned in spaced relationship along such horizontal travel path for such can bodies.
 8. The apparatus of claim 1 in which such conveyance means compriseselongated tubular-configuration endless belt loop means providing for such continuous-line passage through such lubricant deposition chamber, and support means adjustably located at opposite longitudinal ends of such travel path through such lubricant chamber for controllably positioning such endless belts for travel through such lubricant deposition chamber, and belt cleaning means located externally of such deposition chamber in a return path of such loop means for cleaning such endless belts. 